Mechanical fatigue is the accumulation of damage in a structure under applied fluctuating stresses. Though the magnitudes of the applied stresses are less than the tensile strength of the material, the progressive fatigue damage may lead ultimately to mechanical failure. Fatigue life is defined as the number of load cycles necessary to induce failure and it depends on the level of fluctuating strain in the structure. Several fatigue prediction algorithms (e.g. Palmgren-Miner linear rule) rely on counting the number and magnitude of loading cycles applied to a structure. The fatigue in the structure can then be estimated using the cumulative statistics of these applied loads.
Recently, self-powered sensors have been developed for sensing fatigue in mechanical structures. Such sensors capture time compressed data which results in a loss of some information. Therefore, it is desirable to develop robust data interpretation techniques that are able to use the diminished data to achieve reasonable predictive capabilities regarding the damage to a monitored structure.
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